Résumé - Abstract
Insulation covers for mine site reclamation take advantage of the cold climate of arctic regions to maintain mine wastes perennially frozen and below a target temperature in order to limit acid mine drainage generation. Their long-term performance is climate-dependent since their thermal behavior is mainly controlled by air and ground surface temperatures. Hence, it is now recognized that climate change will significantly influence the long-term thermal behavior of insulation covers and, consequently, their capacity to control acid mine drainage.
The construction of in situ experimental cells is a useful tool to assess the thermal behavior of such cover systems and generate data that can be used to calibrate numerical models. This study investigates the performance of two insulation cover configurations, using field experimental cells built in 2011 at Raglan Mine (Nunavik, Quebec). The first tested configuration is a 2.4 m thick insulation cover made of crushed rocks that aims to control the temperature of the tailings based on conduction-dominated heat transfer. The second configuration includes a coarse-grained layer that aims at favoring cold temperature in the tailings via convective cooling. Ground temperature and volumetric water content were monitored at various elevations in the covers and the tailings. Meteorological data from the mine were also available. An analysis of the temperature profiles, and temperature evolution over time at the surface and at the cover-tailings interface provides insight on the behavior of the tested covers over the past 8 to 9 years.